UNIVERSITY   OF   CALIFORNIA    PUBLICATIONS. 


COLLEGE  OF  AGRICULTURE, 


AGRICULTURAL  EXPERIMENT  STATION. 


TOMATO  DISEASES  IN  CALIFORNIA 


By  RALPH  E.  SMITH. 


Blighted  tomatoes  in  re-budded  lemon  orchard. 


BULLETIN     No.     175 


(Berkeley,  Cal.,  January,  1906.) 


SACRAMENTO 


W.    W.    SHANNON, 


SUPERINTENDENT    STATE    PRINTING. 
1906. 


BENJAMIN  IDE  WHEELER,  Ph.D.,  LL.D.,  President  of  the  University 

EXPERIMENT  STATION  STAFF. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Director  and  Chemist.     (Absent  on  leave.) 

E.  J.  WICKvSON,  M.A.,  Acting  Director  and  Horticulturist. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S.,  C.E.,  Irrigation  Engineer. 

C.  W.  WOODWORTH,  M.S.,  Entomologist. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.     (Soils  and  A  Ileal  i.) 

M.  E.  JAFFA,  M.S.,  Assistant  Chemist.     (Foods,  Nutrition?) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Assistant  Chemist.     (Cereals,  Oils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Assistant  Chemist.     (Fruits,  Waters,  Insecticides.) 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian  and  Bacteriologist . 

E.  W.  MAJOR,  B.Agr.,  Animal  Industry. 

RALPH  E.  SMITH,  B.S.,  Plant  Pathologist. 

E.  H.  TWIGHT,  B.Sc,  Diplome  E.A.M.,  Viticulturist, 

F.  T.  BIOLETTI,  M.S.,  Viticulturist. 

WARREN  T.  CLARKE,  B.S.,  Assistant  Entomologist  and  Asst .  Supt.  Farmers'  Institutes. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

GEORGE  ROBERTS,  M.S.,  Assistant  Chemist,  in  charge  of  Fertilizer  Control. 

C.  M.  HARING,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist . 
ALBERT  M.  WEST,  B.S.,  Assistant  Plant  Pathologist. 

E-  H.  SMITH,  M.S.,  Assistant  Plant  Pathologist. 

G.  R.  STEWART,  Student  Assistant  in  Station  Laboratory. 
ALICE  R.  THOMPSON,  B.S.,  Assistant  in  Soil  Laboratory. 

D.  L.  BUNNELL,  Clerk  to  the  Director. 


R.  E-  MANSELL,  Foreman  of  Central  Station  Grounds 

JOHN  TUOHY,  Patron, 

J.  FORRER, 

J.  W.  MILLS,  Pomona,  in  charge.  Cooperation  Experiments  in  Southern  California . 

J.  W.  ROPER,  Patron, 


iHY,  Patron,      ) 

>      Tnlare  Substation,  Tulare. 
L,  Foreman,         ) 


f      Uni 
irge,      ) 


liversitv  Forestry  Station,  Chico. 
HENRY  WIGHTMAN,  In  chat 

ROY  JONES,  Patron,  i 

>      University  Forestry-  Station,rSanta  Monica. 
J.  H.  BARBER,  Foreman,       ) 

VINCENT  J.  HUNTLEY,  Foreman  of  California  Poultry  Experiment  Station,  Petaluma. 


The  Station  publications  (Reports  and  Bulletins),  so  long  as  avail- 
able, iv ill  be  sent  to  any  citizen  of  the  State  on  application. 


TOMATO  DISEASES  IN  CALIFORNIA. 


By  RALPH  E.  SMITH. 


Among  the  losses  caused  by  plant  diseases  in  California  during  the 
past  season,  those  of  the  tomato  grower  have  been  among  the  most 
serious.  In  every  section  of  the  State  where  the  crop  is  extensively 
grown  much  loss  was  occasioned  all  through  the  season  by  tomato 
"  blight,"  and  some  growers  have  become  considerably  discouraged  at 
the  outlook  for  this  crop.  The  present  bulletin  contains  the  results  of 
no  very  extended  investigation  of  the  subject,  but  is  to  be  considered 
rather  as  a  preliminary  report;  the  growers  are  so  entirely  in  the  dark 
as  to  the  cause,  nature,  and  possible  means  of  prevention  of  these 
troubles  that  a  publication  of  what  is  known  upon  the  subject  seems 
justified  at  this  time.  Further  investigation  is  in  progress,  particularly 
as  a  part  of  the  work  of  the  new  pathological  laboratory  for  southern 
California. 

TOMATO    GROWING    IN    CALIFORNIA. 

Canning  Crop. — Tomatoes  are  grown  largely  in  the  State  for  canning, 
and  for  this  purpose  are  usually  planted  to  mature  in  late  summer  and 
fall,  coming  to  the  cannery  after  the  fruit  season  is  over  and  finishing 
the  year's  run.  This  may  be  called  the  main  crop,  and  is  grown  largely 
in  Alameda  and  Santa  Clara  counties,  in  the  San  Joaquin  and  lower 
Sacramento  valleys,  and  in  southern  California. 

Winter  Crop. — Very  recently  there  has  developed  in  certain  prac- 
tically frostless  sections  of  southern  California,  a  profitable  shipping 
trade  in  fall  and  winter  tomatoes,  the  vines  commencing  to  bear  after 
the  beginning  of  cold  weather  in  the  East,  and  continuing  well  into  the 
winter  without  protection.  In  the  usually  dry,  warm  weather  previous 
to  December  1st  a  large  amount  of  fruit  will  set  on  the  vines,  and  it  has 
been  found  that  such  fruit,  maturing  abundantly  in  October,  November, 
and  December  or  later,  may  be  shipped  East  when  the  market  is  prac- 
tically bare,  and  command  a  ready  and  profitable  sale.  This  fruit  is 
picked  in  a  hard-ripe  condition,  carefully  selected,  wrapped  in  paper, 
and  shipped  in  four-box  crates  like  plums  or  peaches.  During  the  past 
fall  nearly  500  acres  of  these  winter  tomatoes  were  grown  in  the  La 
Habra  district,  near  Whittier,  mostly  in  young  walnut  orchards,  and 
more  in  other  sections  about  Los  Angeles.  With  the  canners  paying 
about  $8  per  ton  for  the  summer  crop,  the  rates  of  $30  to  $50  realized 


4  UNIVERSITY    OF    CALIFORNIA  — EXPERIMENT   STATION. 

from  winter  tomatoes  look  very  attractive  and  make  the  business  profit- 
able to  the  grower.  The  production  is  large  and  of  good  quality. 
Altogether  the  growing  of  winter  tomatoes  in  suitable  localities  may 
be  called  a  promising  industry,  capable  of  considerable  further 
development. 

Early  Crop. — In  early  spring  tomatoes  are  planted  by  vegetable 
growers  in  many  parts  of  the  State,  and  these  supply  the  local  markets 
in  the  earlier  part  of  the  season.  This  business  usually  brings  good 
returns,  though  the  production  is  not  so  large  as  in  the  later  crops. 

DISEASES. 

The  tomato  in  California  has  had  but  few  serious  troubles.  The  fruit 
is  not  disposed  to  decay,  and  the  vine  grows  with  extreme  vigor,  except 
when  attacked  by  the  diseases  which  form  the  subject  of  this  bulletin* 
These  may  now  be  taken  up  in  detail. 

DAMPING-OFF. 

Millions  of  tomato  plants  are  lost  some  years  in  the  seed-bed  by 
" damping-off,"  or  stem  rot  of  the  seedlings.  This  trouble,  and  the 
conditions  which  favor  it,  are  well  known  to  most  growers.  During 
periods  of  wet,  continued  cloudy  weather  in  spring,  the  disease  occurs. 
The  little  plants  growing  close  together  wilt  down  on  the  soil,  and  die 
off  in  patches  or  in  whole  beds.  If  examined  more  closely  it  will  be 
seen  that  each  plant  is  affected  with  a  soft  rot  just  at  the  surface  of  the 
ground,  which  cuts  it  off  and  causes  its  death. 

Cause. — The  cause  of  damping-off  is  a  mold-like  fungus,  not  always 
the  same,  which  lives  in  the  soil  and  does  not  always  develop  enough 
to  affect  healthy  plants.  The  conditions  mentioned  of  close,  wet 
weather,  with  little  sunshine  for  some  time,  favor  the  fungus  and 
weaken  the  plant.  Thus  the  former  gets  the  upper  hand,  develops 
very  vigorously  in  the  soil,  and  penetrates  into  the  stem  of  the  weakened, 
delicate  seedling.  This  produces  a  decay,  the  stem  rots  off,  and  the 
fungus  spreads  rapidly  over  the  soil  from  plant  to  plant,  until  a  large 
area  may  be  killed,  if  favorable  conditions  continue.  When  the  sun 
begins  to  shine  again  and  the  soil  is  thereby  dried  off  and  the  young- 
plants  invigorated,  damping-off  is  checked  and  disappears. 

Control.—  It  should  be  kept  in  mind,  in  considering  how  damping-off 
may  be  prevented  or  checked,  that  the  trouble  is  caused  by  a  soil  fungus 
which  is  favored  by  moisture,  cloudy  weather,  weak  plants,  and  any 
condition  which  produces  the  same  effects,  while  its  growth  is  hindered 
by  dryness  and  anything  which  produces  it,  like  sunshine  and  ventila- 
tion.    Seed-beds  should  be  made  of  fresh  soil,  free  from  anything  con- 


TOMATO  DISEASES  IN   CALIFORNIA.  O 

nected  with  previous  crops  of  tomatoes.  The  seed  should  not  be  planted 
too  thickly,  as  a  close,  dense  growth  of  the  plants  greatly  favors  damp- 
ing-off. After  the  seedlings  appear,  the  surface  of  the  ground  should 
be  kept  as  dry  as  possible  by  stirring,  covering  the  beds  during  rain, 
opening  to  let  in  all  possible  sun  and  wind,  and  watering  as  little  as 
possible. 

At  times  when  the  weather  is  bad  the  plants  wrill  sometimes  commence 
dying  in  spite  of  all  these  precautions.  At  such  times  it  is  difficult  to 
stop  the  spread  of  the  trouble  by  any  treatment.  Some  growers  have 
sprinkled  sulfur  thickly  over  the  young  plants,  and  report  some  success 
in  checking  the  disease.  A  sprinkling  of  air-slaked  lime  may  also  have 
a  beneficial  effect  by  drying  and  covering  the  surface  of  the  soil. 
Further  treatment  consists  in  spraying  the  plants  and  soil  heavily  with 
a  weak  Bordeaux  mixture  (3  pounds  of  lime,  3  pounds  of  Milestone, 
and  50  gallons  of  water),  in  order  to  check  the  spread  of  the  fungus 
over  the  surface  of  the  soil.  Such  a  spraying,  combined  with  a  sprink- 
ling of  dry  sulfur,  will  check  damping-off,  as  much  as  can  be  done  by 
any  means  at  times  of  continuous  dull  weather  with  conditions  favor- 
able to  the  disease.  If  a  bed  becomes  badly  affected,  it  is  better  to  let 
it  go  altogether  and  start  new  plants  in  fresh  soil. 

Soil  sterilization  by  means  of  steam  for  the  purpose  of  exterminating 
soil  fungi  has  never  been  attempted  in  California,  but  is  being  practiced 
quite  extensively  in  certain  Eastern  sections  for  hot-houses,  cold  frames, 
etc.  The  method  is  simple,  and  kills  every  form  of  parasitic  or  other 
life  in  the  soil  treated.  Perforated  pipe  or  tile  is  placed  in  the  soil  in 
a  gridiron  arrangement,  buried  to  a  depth  of  about  a  foot,  and  steam 
then  turned  in  from  a  boiler  and  kept  up  for  some  time.  The  soil 
becomes  permeated  with  the  hot  steam  and  all  fungus  spores,  weed 
seeds,  insects  and  their  eggs,  etc.,  are  destroyed.  The  growth  of  plants 
in  soil  after  such  treatment  is  also  considerably  stimulated.  For  large 
growers  of  tomato  or  other  plants  who  are  losing  seriously  by  damping- 
off,  this  method  is  worth  considering.  The  writer  will  be  pleased  to 
give  further  details  to  any  one  interested  in  the  subject. 

SUMMER    BLIGHT. 

Under  the  term  "blight"  is  commonly  designated  in  California  a 
tomato  disease  which  is  known  everywhere  in  the  State  in  greater  or 
less  abundance,  and  occurs  not  infrequently  as  the  cause  of  losses  up  to 
100  per  cent  of  plants  between  half-grown  and  maturity.  This  is  here 
termed  the  "summer  blight,"  to  distinguish  it  from  another  disease  to 
be  described  later.  The  disease  seems  to  have  been  known  longest  in 
its  severe  form  in  the  San  Joaquin  Valley.  Losses  of  entire  fields  of 
good-sized  plants  have  been  known  there  for  several  years,  and  in  fact 
this  has  come  to  be  almost  the  rule  in  that  section.     In  Alameda   and 


6  UNIVERSITY   OP    CALIFORNIA — EXPERIMENT   STATION. 

Santa  Clara  counties  the  disease  has  frequently  been  seen  on  occasional 
plants,  but  has  not  been  considered  as  of  any  serious  importance. 
In  southern  California  this  blight  has  been  the  cause  of  considerable 
loss  in  recent  years.  In  1905  the  disease  was  probably  more  general 
than  ever  before,  completely  ruining  many  fields  in  southern  California, 
almost  all  in  the  San  Joaquin,  and  causing  a  loss  of  from  1  to  50  per 
cent  of  the  plants  in  fields  all  over  the  State. 

The  principal  effects  of  this  disease  are  seen  in  the  main  or  canning 
crop  of  tomatoes  grown  in  summer,  and  in  the  last  of  the  early  crop. 


FIG.  1.    Tomato  plant  affected  by  Summer  Blight. 


The  plants,  after  being  set  out,  usually  reach  considerable  size,  blossom- 
ing and  setting  fruit  before  showing  the  disease.  It  first  appears 
here  and  there  in  the  field  on  single  plants,  which  begin  to  fall  behind 
the  others  in  growth,  grow  somewhat  spindling  and  generally  sickly 
looking,  and  gradually  turn  to  a  dull,  unhealthy  color  and  begin  to 
wilt.  The  leaves  do  not  blacken  or  suddenly  die,  but  the  whole  plant, 
gradually  sickens,  wilts,  fades  away,  and  finally  collapses  upon  the 
ground  and  becomes  entirely  dead.  The  disease  comes  on  gradually  in 
the  field,  affecting  plants  here  and  there  in  a  very  scattering  manner. 
In  the  worst  cases  they  all  die  before  the  summer  is  over,  and  some- 
times all  quite  suddenly  at  the  last;  again,  the  field  goes  through  in  a 


TOMATO  DISEASES  IN   CALIFORNIA.  7 

spotted  condition,  with  plants  missing  more  or  less  extensively.  If  a 
badly  affected  or  dead  plant  be  pulled  up,  the  roots  are  found  to  be  de- 
cayed or  destroyed.  When  first  affected  this  is  not  the  case;  if  a  plant 
is  pulled  up  as  soon  as  it  begins  to  show  wilting  and  fading,  the  roots 
look  healthy  and  sound.  But  if  such  plants  be  carefully  dug,  to  avoid 
breaking  off  the  smaller  roots,  it  will  be  seen  that  many  of  the  larger 


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FIG.  2.     Cross-section  of  Tomato  root,  showing  woody  portion  wifh  Fnsarium  fungus 

in  large  water  ducts. 

laterals  are  decayed  at  the  ends  and  in  bad  condition.  These  parts  are 
broken  off,  and  very  likely  are  not  noticed  if  the  plant  is  pulled  out  of 
the  ground  by  force.  By  careful  digging  any  plant  which  shows  the 
symptoms  of  the  disease  at  all  can  be  seen  to  be  affected  in  the  manner 
of  a  dry  rot  of  the  roots,  commencing  at  the  ends  and  working  up. 

Cause. — This  trouble  has  been  commonly  referred  to  as  the  bacterial 
blight,  an  Eastern  tomato  disease.  It  is  not  that  disease,  however,  nor 
has  the  latter,  so  far  as  the  writer  is  aware,  ever  been  found  in  this 


8  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

State.  The  effect  is  somewhat  similar,  though  not  decidedly  so.  In 
the  California  disease  the  decayed  roots  show  at  all  times  a  typical 
root-rot  fungus  of  the  Fusarium  type.  Fungi  of  this  sort  live  in  the 
soil  and  cause  root  or  stem  rot  diseases  of  a  great  variety  of  plants. 
The  fungus  grows  into  the  roots  and  flourishes  particularly  in  the  large 
water-conveying  ducts  of  the  central  portion.  These  become  filled 
with  the  fungous  growth  and  the  supply  of  water  is  cut  off  from  the 
plant  above.  (See  Fig.  2.)  The  present  disease  is  now  under  investi- 
gation by  this  department,  particularly  as  to  the  identity  of  the 
Fusarium,  and  the  manner  of  infection  of  the  plant.  Affected  plants 
obtained  last  season  from  Yuba  City,  Fresno,  Merced,  Niles,  Milpitas, 
Los  Angeles,  and  Whittier  showed  in  all  cases  a  disease  apparently  the 
same.  The  root  decay  seemed  always  to  begin  at  the  ends  of  the 
smaller  roots,  at  a  considerable  depth  in  the  soil,  gradually  working  up 
into  the  tap-root.  The  plant  above  ground  remains  free  from  the 
fungus,  simply  wilting  and  dying  from  starvation  and  lack  of  water. 
How  the  fungus  spreads  and  in  what  manner  plants  first  become 
infected  are  questions  which  must  be  determined  before  any  definite 
method  of  prevention  can  be  suggested.  Growers  state  that  the  disease 
occurs  abundantly  in  plants  started  in  new  soil  and  planted  in  new 
land.  It  is  hoped  to  determine  this  and  other  important  points  during 
the  coming  season. 

A  Fusarium  disease  of  watermelon  is  very  prevalent  in  some  locali- 
ties where  the  tomato  trouble  occurs,  but  whether  the  two  have  any 
connection  has  not  yet  been  determined.  There  also  appears  to  be  at 
least  one  very  common  species  of  Fusarium  indigenous  to  our  soil.*  In 
the  Fusarium  disease  of  the  garden  aster  described  by  the  writer  in 
1901  (Bulletin  No.  79,  Massachusetts  Experiment  Station)  it  was  found 
that  plants  which  died  in  the  field  were  only  those  which  had  become 
infected  in  the  seed-bed,  while  healthy  plants  did  not  get  the  disease 
after  being  set  out  in  the  field.  In  this  case  the  Fusarium  caused  a 
damping-off  of  the  seedlings.  The  latter  is  also  apparently  true  with 
tomatoes,  though  the  matter  has  not  yet  been  thoroughly  investigated. 
The  California  tomato  disease  appears  somewhat  different  from  the 
"Sleeping  Disease"  or  wilt,  described  as  being  caused  by  Fusarium 
lycopersici  Sacc,  being  strictly  a  root  rot,  confined  to  the  soil. 

Control. — Pending  further  investigation  of  this  disease,  little  can  be 
said  concerning  methods  for  its  control.  Great  care  should  be  taken 
to  make  the  seed-bed  of  absolutely  new  material,  and  to  plant  the  field 
where  the  disease  has  not  occurred.  Spraying  the  tops  is  perfectly 
useless,  since  the  trouble  is  entirely  below  ground.  Experimental 
plantings  are  planned  for  this  year,  on  infected  and  new  soil,  both  in 

*Mr.  C.  0.  Smith,  a  graduate  student  of  the  College  of  Agriculture  of  the  University, 
is  at  present  engaged  in  a  study  of  all  the  Fusaria  occurring  in  the  State. 


TOMATO  DISEASES  IN   CALIFORNIA.  9 

the  seed-bed  and  field,  and  on  sterilized  soil.  Methods  of  soil  treatment 
will  also.be  considered.  The  matter  of  resistant- varieties  is  also  worthy 
of  some  attention,  particularly  in  selecting  seed  from  resistant  plants  in 
fields  where  the  disease  is  abundant. 

WINTER    BLIGHT. 

During  the  past  fall  a  disease  of  an  entirely  different  nature  from 
that  just  described  has  come  upon  the  winter  tomato  fields  of  the  La 
Habra  and  other  southern  districts,  and  completely  ruined  them. 
In  the  district  mentioned  the  shipments  fell  off  within  a  very  short 
time  from  3,000  crates  per  day  to  practically  nothing,  and  at  a  time 
when  an  increase  should  have  been  taking  place.  Many  thousands  of 
dollars  were  lost  to  the  growers  from  this  cutting-orr  of  the  crop  just  at 
the  most  profitable  season.  The  disease  which  brought  about  this 
result  may  be  designated  by  the  above  name  according  to  the  season  of 
its  occurrence,  to  distinguish  it  from  the  summer  disease  or  blight.  It 
may  be  said  here  that  the  Fusarium  disease  does  not  seem  to  continue 
into  the  fall,  the  late  crops  showing  very  little  of  this  trouble. 

After  the  recent  heavy  November  rains  in  southern  California,  tomato 
picking  and  shipping  were  just  approaching  the  height  of  the  season. 
The  vines  were  covered  with  green  fruit,  good  returns  had  already  been 
made,  and  an  excellent  prospect  was  in  sight.  Quite  suddenly,  how- 
ever, in  the  early  part  of  December  or  last  of  November,  this  winter 
blight  appeared  and  ruined  the  crop.  The  period  was  one  of  warm 
days  and  cold  nights,  following  heavy  rain.  The  disease  appeared 
quite  differently  from  the  former  blight.  There  was  no  wilting  or 
gradual  dying  of  the  vines,  but  there  first  appeared  dark,  discolored 
spots  on  the  fruit,  stems,  branches,  and  leaves.  On  the  fruit  (Fig.  3)  a 
discolored,  watery  spot  develops,  usually  on  the  upper  side,  and  there- 
fore mostly  near  the  stem  end.  This  increases  quite  rapidly,  several 
spots  appear  on  one  tomato,  and  it  soon  rots  and  is  spoiled.  Fruit  of 
all  sizes  is  affected,  from  the  smallest  to  that  ready  to  pick.  When 
sound-appearing  fruit  is  picked  from  affected  vines,  many  of  the  tomatoes 
develop  the  spots  and  rot  in  the  box  within  a  few  days.  In  moist 
weather  a  white,  mildew-like  mold  comes  out  abundantly  on  the  affected 
spots.  On  the  stems  and  branches  dark  spots  appear  (Fig.  4),  and  soon 
the  whole  vine  becomes  black  and  dead,  with  green  tufts  remaining 
here  and  there,  exactly  as  though  the  field  had  been  struck  by  frost. 
In  many  cases  this  blight  was  mistaken  for  the  effects  of  frost,  when  no 
frost  had  occurred.  In  blighted  fields  the  ground  remained  covered 
with  tomatoes,  all  spotted,  infected  with  rot,  and  worthless. 

Cause. — This  trouble  proved  to  be  a  common  disease  of  another 
plant  which  sometimes  attacks  the  tomato,  but  very  seldom  as  seriously 
as  this.     It  is  the  potato  blight  or  mildew,  well  known  to  every  Eastern 


10 


UNIVERSITY    OP    CALIFORNIA  — EXPERIMENT    STATION. 


potato-grower  as  the  cause  of  great  losses  in  potatoes,  both  as  a  blight 
of  the  tops  and  rotting  of  the  tubers.     The  cause  is  a  parasitic  fungus 


FIG.  3.    Tomatoes  spotted  and  decayed  by  Phytophthora,  or  Winter  Blight. 

(Phytophthora  infestans  D.By.),  and  this  same  fungus  was  the  cause  of 
the  winter  blight  of  the  tomato.     It  is  a  disease  which  is  greatly  favored 


TOMATO  DISEASES  IN   CALIFORNIA. 


11 


by  wet  weather,  and  for  that  reason  attacked  the  tomatoes  when  it  did, 
but  such  a  destructive  effect  in  this  crop  is  quite  unusual.     There  seems? 


FIG.  4.    Tomato  branch  affected  by  Phytophthora. 

indeed,  to  be  no   case  recorded  where  Phytophthora  has   affected   the 
tomato  to  such  an  extent  as  this.     The  fungus  is  identical  in  every  way 


12 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 


with    that  of  the   potato,  showing  the  characteristic  swellings  of  the 
conidiophores,  and  growing  readily  on  the  cut  surface  of  potatoes. 


Oh 


T3 


S3 
C 
03 
? 
5* 

5 

o 


c 

o 

o 


^ 


The  white  mildew  seen   on  the   surface  of  affected  tomatoes  is  the 
fungus  which  is  responsible  for  the  disease.     It  consists  of  fine,  branch- 


TOMATO   DISEASES   IN   CALIFORNIA. 


13 


ing  threads  which  grow  into  the  fruit  and  branches,  producing  the  rot- 
ting and  discoloration.  (Fig.  6.)  The  filaments  also  grow  out  on  the 
surface  in  moist  air,  and  on  the  tips  of  these  aerial  filaments,  the 
sporangiophores,  are  produced  the  egg-shaped  spores  of  the  fungus. 
(Fig.  7.)  These  soon  drop  off  and  are  scattered  by  the  wind  in  all 
directions.     Their  further  development  is  somewhat  peculiar.     Instead 


FIG.  6.    Tissue  of  tomato,  with  filaments  of  Phytophthora. 


of  simply  sprouting  and  forming  new  filament  threads  like  most  spores, 
the  contents  of  each  one  divide  inside  into  a  number  of  smaller  spores, 
called  swarm-spores.  The  original  spore,  or  sporangium,  then  opens  at 
the  end  and  the  little  swarm-spores  now  out.  Each  one  is  provided  on 
the  side  with  two  fine  cilia,  or  tail-like  appendages.  By  means  of  these 
they  are  able  to  swim  vigorously  about  in  drops  of  rain  wrater,  dew,  or 
any  moisture,  so  that  by  the  wind  blowing  the  sporangia,  which  them- 
selves are  only  about  one  one-thousandth  of   an  inch  in  diameter,  and 


14 


UNIVERSITY    OF    CALIFORNIA  — EXPERIMENT    STATION. 


the  swimming  of  the  swarm-spores,  the  disease  is  able  to  spread  rapidly 
in  wet  weather.     (Fig.  8.)    The  swarm-spores  finally  come  to  rest,  sprout, 


FIG.  7.    Surface  growth  of  Phytophlhora  on  tomato,  showing  formation  of  sporangia. 


FIG.  8.    Formation  of  swarm-spores  of  Phytophlhora: 

and  if  situated  on  a  potato  or  tomato  plant  the  filaments  grow  into  the 
tissue,  a  new  black  spot  appears,  and  the  blight  increases. 


TOMATO   DISEASES  IN   CALIFORNIA.  15 

In  dry  weather  this  disease  is  not  to  be  feared,  as  it  can  only  develop 
with  an  abundance  of  moisture.  For  this  reason  it  is  comparatively 
rare  on  potatoes  in  California,  only  occurring  occasionally  in  sections 
or  seasons  with  a  great  deal  of  rain  or  very  heavy  dews.  Potato  blight 
is  not  uncommon  in  the  coast  section  of  Monterey  County,  and  occurred 
extensively  about  Sacramento  on  the  fall  crop  of  1904  and  the  spring 
crop  of  1905,  both  being  seasons  of  a  large  amount  of  rain.  The  group 
of  fungi  to  which  Phytophthora  belongs,  the  Peronosporese,  all  show  the 
same  moisture  requirement  and  are  comparatively  rare  in  California. 
The  downy  mildew  of  the  grape  (Plasmopara  viticola  Berk.)  is  particu- 
larly conspicuous  by  its  absence.  The  onion  mildew  (Peronospora  schlei- 
deni  Ung.)  becomes  abundant  and  troublesome  in  our  great  seed  fields 
only  in  unusually  wet  seasons.  The  relation  of  the  Phytophthora,  or 
winter  blight,  to  the  tomato  crop  is  therefore  very  positively  one  of 
moisture,  and  the  disease  need  not  be  feared  or  considered  at  all  in  the 
summer  crop,  or  at  any  time  except  when  there  is  much  moisture  in 
the  air  from  continuous  heavy  fog  or  rain. 

Treatment. — The  control  of  this  disease  has  been  thoroughly  worked 
out  in  Eastern  States  for  potatoes,  and  the  same  methods  will  no  doubt 
prove  effective  here.  Treatment  consists  in  spraying  with  Bordeaux 
mixture;  in  climates  with  frequent  rains  in  summer  this  is  done  several 
times  at  regular  intervals,  in  order  to  keep  the  vines  well  covered  with 
spray  at  all  times.  In  California  this  would  not  be  necessary.  Spray- 
ing should  be  regulated  entirely  by  the  rainfall.  If  there  is  no  rain 
there  is  no  danger  whatever  of  winter  blight,  and  no  need  of  spraying. 

If  rains  occur  while  the  vines  are  in  growing  or  bearing  condition, 
spray  thoroughly  with  Bordeaux  mixture  immediately  after  the  rain 
stops.  If  there  should  be  frequent  showers  a  day  or  a  few  days  apart, 
spray  between  showers  rather  than  wait  too  long.  Aim  to  cover  the 
fruit  and  all  parts  of  the  vine  with  the  spray.  If  the  mixture  shows  on 
the  fruit  when  picked,  it  can  be  easily  wiped  off.  Bordeaux  mixture  is 
not  poisonous.  Repeat  the  spraying  after  the  next  rain,  if  any  occurs; 
but  continued  spraying  in  dry  weather  is  not  necessary.  One  good 
spraying  at  the  right  time  last  fall  would  probably  have  saved  thou- 
sands of  dollars  in  the  winter  tomato  crop 

It  is  advisable,  in  regard  to  this  disease  on  general  principles,  not  to 
plant  tomatoes  on  the  same  land  one  year  after  another,  although  the 
Phytophthora  spreads  so  rapidly  when  conditions  are  favorable  that 
this  precaution  could  have  little  effect  in  preventing  the  blight. 

SUMMARY. 

Three  serious  tomato  diseases  occur  in  California. 
"Damping -Off"  is  a  stem  rot  of  the  young  plants  in  the   seed-bed, 
which  occurs  mostly  in  wet,  cloudy  weather  or  in  seed-beds  which  are 


16  UNIVERSITY    OF    CALIFORNIA  — EXPERIMENT    STATION. 

over  watered  or  poorly  ventilated.  It  is  caused  by  a  fungus  or  various 
fungi  which  spread  on  the  surface  of  the  ground  under  such  con- 
ditions and  kill  the  young  plants.  To  prevent  this  trouble  it  is 
necessary  to  use  fresh  earth  in  the  seed-bed,  keep  the  soil  dry  on  top, 
ventilate  the  beds  well,  and  avoid  overcrowding  the.  plants.  To  check 
the  disease  when  started,  spraying  the  soil  and  plants  with  weak  Bor- 
deaux mixture,  followed  by  a  sprinkling  of  sulfur,  is  recommended. 
A  trial  of  soil  sterilization  by  means  of  steam  is  suggested  to  large 
growers. 

"Summer  Blight"  is  a  wilt  and  gradual  dying  of  mature  or  partly 
grown  plants  in  the  field,  which  occurs  extensively  in  the  San  Joaquin 
Valley  and  southern  California,  and  somewhat  in  the  San  Francisco 
Bay  region,  mostly  in  the  summer  crop.  The  disease  is  caused  by  a 
species  of  Fusarium,  a  soil  fungus,  which  causes  a  dry  rot  of  the  roots 
and  cuts  off  the  supply  of  soil  water  from  the  plant.  This  disease 
forms  one  of  the  present  subjects  of  investigation  by  this  department. 
At  present  the  only  recommendations  which  can  be  made  consist  in 
taking  great  pains  to  obtain  healthy  plants,  and  planting  in  new  soil. 
Applications  of  lime,  sulfur,  etc.,  to  the  soil  may  be  tried  by  the 
grower,  but  the  effect  of  such  treatment  has  not  yet  been  demonstrated. 
Spraying  can  not  be  of  any  use  with  this  disease. 

"  Winter  Blight  "  is  a  disease  caused  by  the  potato-blight  fungus, 
Phytophthora  infestans,  which,  under  favorable  conditions,  has  seriously 
affected  winter  tomatoes  in  southern  California.  The  same  trouble 
was  observed  on  potatoes  in  Sacramento  County  in  the  fall  of  1904 
and  spring  of  1905,  and  in  the  coast  region  of  Monterey  County,  but  is 
not  very  prevalent  in  California.  This  fungus  causes  a  spotting  of 
green  and  ripe  tomatoes,  dark  spots  on  the  stems  and  branches,  and 
complete  and  sudden  ruin  of  the  crop.  It  occurs  only  after  heavy  rains 
or  very  heavy  fogs  and  dews,  and  consequently  affects  only  the  winter 
crop  of  tomatoes.  Such  plantings  should  be  sprayed  heavily  with 
Bordeaux  mixture  after  every  rain  to  prevent  the  development  of  this 
form  of  blight. 

DIRECTIONS  FOR  PREPARING  BORDEAUX  MIXTURE. 

Bluestone    5  lbs. 

Quicklime 5  lbs. 

Water 50  gals. 

Dissolve  the  bluestone  and  slake  the  lime  in  separate  barrels.  Dilute 
the  bluestone  with  half  or  more  of  the  water,  then  strain  in  the  lime 
mixed  with  the  remainder  of  the  50  gallons  of  water.  Use  while  freshly 
prepared. 


STATION  PUBLICATIONS  AVAILABLE  FOR  DISTRIBUTION. 


REPORTS. 


1896.  Report    of    the    Viticultural    Work    during    the    seasons    1887-93,    with    data 

regarding  the  Vintages  of  1894-95. 

1897.  Resistant    Vines,    their    Selection,    xVdaptation,    and    Grafting.      Appendix    to 

Viticultural  Report  for  1896. 

1898.  Partial   Report  of  Work  of  Agricultural   Experiment   Station   for  the  years 

1895-96  and  1896-97. 
1900.     Report  of  the  Agricultural  Experiment  Station  for  the  year  1897-98. 

1902.  Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

1903.  Report  of  the  Agricultural  Experiment  Station  for  1901-1903. 

1904.  Twenty-second  Report  of  the  Agricultural  Experiment  Station  for  1903-1904. 

BULLETINS. 

Reprint.  Endurance  of  Drought  in  Soils  of  the  Arid  Region. 

No.  128.  Nature,  Value,  and  Utilization  of  Alkali  Lands,  and  Tolerance  of  Alkali. 
(Revised  and  Reprint,  1905.) 

131.  The  Phylloxera  of  the  Vine. 

133.  Tolerance  of  Alkali  by  Various  Cultures. 

135.  The  Potato-Worm  in  California. 

137.  Pickling   Ripe   and   Green   Olives. 

138.  Citrus  Fruit  Culture. 

139.  Orange  and  Lemon  Rot. 

140.  Lands  of  the  Colorado  Delta  in  Salton  Basin,  and  Supplement. 

141.  Deciduous  Fruits  at  Paso  Robles. 

142.  Grasshoppers  in  California. 

143.  California  Peach-Tree  Borer. 

144.  The  Peach- Worm. 

145.  The  Red  Spider  of  Citrus  Trees. 

146.  New  Methods  of  Grafting  and  Budding  Vines. 

147.  Culture  Work  of  the  Substations. 

148.  Resistant  Vines  and  their  Hybrids. 

149.  California  Sugar  Industry. 

150.  The  Value  of  Oak  Leaves  for  Forage. 

151.  Arsenical  Insecticides. 

152.  Fumigation  Dosage. 

153.  Spraying  with  Distillates. 

154.  Sulfur  Sprays  for  Red  Spider. 

155.  Directions  for  Spraying  for  the  Codling-Moth. 

156.  Fowl  Cholera. 

157.  Commercial  Fertilizers. 

158.  California   Olive  Oil ;   its  Manufacture. 

159.  Contribution  to  the  Study  of  Fermentation. 

160.  The  Hop  Aphis. 

161.  Tuberculosis  in  Fowls.      (Reprint.) 

162.  Commercial  Fertilizers.      (Dec.  1,  1904.) 

163.  Pear  Scab. 

164.  Poultry  Feeding  and  Proprietary  Foods.      (Reprint.) 

165.  Asparagus  and  Asparagus  Rust  in  California. 

166.  Spraying  for  Scale  Insects. 

167.  Manufacture  of  Dry  Wines  in  Hot  Countries. 

168.  Observations  on  Some  Vine  Diseases  in  Sonoma  County. 

169.  Tolerance  of  the  Sugar  Beet  for  Alkali. 

170.  Studies  in  Grasshopper  Control. 

171.  Commercial  Fertilizers.     (June  30.  1905.) 

172.  Further  Experience  in  Asparagus  Rust  Control. 

173.  Commercial  Fertilizers.      (December,  1905.) 

174.  A   New   Wine-Cooling  Machine. 

CIRCULARS. 

No.  1.  Texas  Fever.  No.   13.     The  Culture  of  the  Sugar  Beet. 

2.  Blackleg.  14.     Practical    Suggestions    for   Cod- 

3.  Hog  Cholera.  ling-Moth      Control      in      the 

4.  Anthrax.  Pajaro  Valley. 

5.  Contagious  Abortion  in  Cows.  15.  Recent  Problems  in  Agriculture. 
7.  Remedies  for  Insects.  What  a  University  Farm  is 
9.  Asparagus  Rust.  For. 

10.  Reading    Course    in    Economic  16.     Notes   on    Seed- Wheat. 

Entomology.  17.     Why     Agriculture      Should      be 

11.  Fumigation  Practice.  Taught  in  the  Public  Schools. 

12.  Silk  Culture. 

Copies  may  be  bad  by  application  to  the  Director  of  the  Experiment 
Station,  Berkeley,  California. 


